2015年11月10日火曜日

UIST2015 Fabrication 1: Augmentation

One powerful aspect of 3D printing is its ability to extend, repair, or more generally modify everyday objects. However, nearly all existing work implicitly assumes that whole objects are to be printed from scratch. Designing objects as extensions or enhancements of existing ones is a laborious process in most of today’s 3D authoring tools. This paper presents a framework for 3D printing to augment existing objects that covers a wide range of attachment options. We illustrate the framework through three exemplar attachment techniques – print-over, print-to-affix and print-through, implemented in Encore, a design tool that supports a set of analysis metrics relating to viability, durability and usability that are visualized for the user to explore design options and tradeoffs. Encore also generates 3D models for production, addressing issues such as support jigs and contact geometry between the attached part and the original object. Our validation helps to illustrate the strengths and weaknesses of each technique. For example, print-over is stronger than print-to-affix with adhesives, and all the techniques’ strengths are affected by surface curvature.

How to keep sustainability of 3D printed objects?
> Not to reprint every time, but to patch/edit the printed objects.
Print > re-scan the old 3D model to patch.

Personal fabrication is currently a one-way process: Once an object has been fabricated with a 3D printer, it cannot be changed anymore; any change requires printing a new version from scratch. The problem is that this approach ignores the nature of design iteration, i.e. that in subsequent iterations large parts of an object stay the same and only small parts change. This makes fabricating from scratch feel unnecessary and wasteful.

In this paper, we propose a different approach: instead of re-printing the entire object from scratch, we suggest patching the existing object to reflect the next design iteration. We built a system on top of a 3D printer that accomplishes this: Users mount the existing object into the 3D printer, then load both the original and the modified 3D model into our software, which in turn calculates how to patch the object. After identifying which parts to remove and what to add, our system locates the existing object in the printer using the system’s built-in 3D scanner. After calibrating the orientation, a mill first removes the outdated geometry, then a print head prints the new geometry in place. Since only a fraction of the entire object is refabricated, our approach reduces material consumption and plastic waste (for our example objects by 82% and 93% respectively).

Digital fabrication machines such as 3D printers and laser-cutters allow users to produce physical objects based on virtual models. The creation process is currently unidirectional: once an object is fabricated it is separated from its originating virtual model. Consequently, users are tied into digital modeling tools, the virtual design must be completed before fabrication, and once fabricated, re-shaping the physical object no longer influences the digital model. To provide a more flexible design process that allows objects to iteratively evolve through both digital and physical input, we introduce bidirectional fabrication. To demonstrate the concept, we built ReForm, a system that integrates digital modeling with shape input, shape output, annotation for machine commands, and visual output. By continually synchronizing the physical object and digital model it supports object versioning to allow physical changes to be undone. Through application examples, we demonstrate the benefits of ReForm to the digital fabrication process.

To fabricate functional objects, designers create assemblies combining existing parts (e.g., mechanical hinges, electronic components) with custom-designed geometry (e.g., enclosures). Modeling complex assemblies is outside the reach of the growing number of novice ``makers'' with access to digital fabrication tools. We aim to allow makers to design and 3D print functional mechanical and electronic assemblies. Based on a formative exploration, we created Makers' Marks, a system based on physically authoring assemblies with sculpting materials and annotation stickers. Makers physically sculpt the shape of an object and attach stickers to place existing parts or high-level features (such as parting lines). Our tool extracts the 3D pose of these annotations from a scan of the design, then synthesizes the geometry needed to support integrating desired parts using a library of clearance and mounting constraints. The resulting designs can then be easily 3D printed and assembled. Our approach enables easy creation of complex objects such as TUIs, and leverages physical materials for tangible manipulation and understanding scale. We validate our tool through several design examples: a custom game controller, an animated toy figure, a friendly baby monitor, and a hinged box with integrated alarm.

Disclaimer: The opinions expressed here are my own, and do not reflect those of my employer. -Fumi Yamazaki